孔隙度测定误差及其控制方法研究

随着油气勘探领域的扩大，孔隙度测试样品的岩性及形态呈现多样化的发展趋势。在生产与科研实践中发现，相同的样品不同实验室孔隙度测定结果存在差异，给孔隙度资料的应用带来了困扰，孔隙度测定面临着新的挑战。从影响孔隙度测定结果的岩样总体积和骨架体积2个关键参数入手，分析了其测试误差对孔隙度测定结果的影响，发现测试相对误差为0.5%，1.0%，1.5%时，造成的孔隙度绝对误差分别为0.5，0.9，1.4，二者的测试误差对孔隙度测定精度的影响程度相近，应该予以有效控制；分析了岩样骨架体积和总体积测试误差控制现状，认为岩样骨架体积测试依托较为成熟的方法和装置，测试误差能够得到有效控制。总体积测试技术发展滞后，测定过程中关键参数获取受随机的人为因素影响，导致不同操作人员及不同实验室测定结果存在差异。探讨了有效控制孔隙度测定误差的方法，介绍了基于流体变密度测定原理的岩石样品总体积测定系统。该系统对样品的岩性和形态没有限制性要求，实现了岩样总体积测定的自动化；可以减少人为因素对测试的影响，岩样总体积测定平均相对误差0.5%，能够将孔隙度测定绝对误差控制在0.5左右，可用来缩小不同实验室测定结果差异。

Porosity measurement error and its control method

With the expansion of oil and gas exploration, the lithology and morphology of porosity test samples show diverse development trends. Porosity measurement faces new challenges because the same sample may have different laboratory porosity measurement results, limiting the application of porosity data. Starting from two key parameters of the total volume and skeleton volume of the rock sample, the influence of test error on the porosity measurement results was analyzed. It is found that when the relative error of the test is 0.5%, 1.0% and 1.5%, the absolute error of porosity is 0.5, 0.9 and 1.4, respectively. The test error of the two has similar influence on the accuracy of porosity measurement, and should be effectively controlled. The current situation of error control of rock sample skeleton volume and total volume was analyzed. Volume testing relies on more mature methods and devices, and its test error can be effectively controlled. The development of total volume testing technology lags behind. The acquisition of key parameters in the measurement process is affected by random human factors, resulting in differences between different operators and different laboratory results. The method for effectively controlling porosity measurement error was discussed. A total sample volume measurement system for rock samples based on the fluid density determination principle was introduced, which has no restrictive requirements on the lithology and morphology of the sample, and automates the determination of the total volume of rock sample. The influence of human factors on the test can be reduced. The average relative error of the total volume of rock sample is 0.5%, and the absolute error of porosity measurement can be controlled to about 0.5, which can be used to narrow the difference of measurement results in different laboratories.